Carburetor



n June 10, 1930. H. w. LINKERT CARBURETOR Filed March 14 lagig.

Patent-ed `.lume 1o, r1930 UNITED STATES PATENT` oFFicE HOWARD W. LINKRT, OF INDIANAPOLIS, INDIANA, ASSIGNOR TO THE WHEELER- vSCIHIEBLER. CARBURETOR CO., OF INDIANAPOLIS, INDIANA, A. CORPORATION OF INDIAN A 'CARBURETOR qApplication filed March 14, 1925. Serial No. 15,468.

In the operation of liquid-fuel carburetors and their associated engines, one of the conditions which tends to interfere with proper operation is the introduction into the engine 5'of too rich a mixture at the beginning of idling, following a period of operation under low suction, especially when such low suction is accompanied by low air velocity. This frequently results in a stopping of the engine,

generally known as dying or stalling,

When a carburetor using liquid fuel is operating under low suction and low air velocity, the liquid fuel collects in considerable quantity on the various surfaces within the passage for explosive mixture, as on the manifold, walls' and on the carburetorthrottle disk and shaft. When the suction is suddenly raised, as upon closing the throttle from wide-open position to idling `llfposition, this collected fuel is added to the normal idling mixture; which makes the mixture so rich that it will not ignite, and so causes the engine to stop.

Moreover, with many carburetors it is diiicult to start a motor, especially when the motor is hot, when the throttle is closed; because of an insutlicient quantity of mixture, or because the mixture is too rich from fuel which has remained in the intake passages from the previous operation, or both. The attempts to start motorswith closed throttles have therefore caused much trouble, with.

heavy drain on the battery supplying the starter. f l

It is the object of my present invention to avoid these difficulties. The primary object is to lessen the danger of having the motor stop upon the closing of the throttle to idling position. A secondary object is to facilitate starting, especially with a hot motor.

More specifically, it is ythe object of my invention to provide an increased supply of air in the mixture that reaches the engine in the early part of a period of idling; and, secondarily, to ensure a larger supply of explosive mixture to the engine during startin In carrying out my invention, I provi e means for admitting an additional supply of air, (desirably by admittin explosive mix- 50 ture, which contains air, fgrom the mixing .which operates to close such passage or conduit after a predetermined time following the beginning of a high-suction condition above the throttle.

The details of this will appear hereinafter.

The accompanying drawing illustrates my invention: Fig. 1 is a fragmentary vertical section through a carburetor embodying my invention in its preferred form, only part of the carburetor being shown; and Fig. 2 is a similar fragmental view, showing a detail l of a modification.

My invention is applicable to carburetors of any design; but is of especial value in connection with the carburetor invented by Otto Carter Berry and myself, shown in our copending application Serial No. 639,131, liled May 15, 1923, so that I have used that carburetor to illustrate myy invention. In that carburetor, as in others, it is important to prevent t'oo great enrichment of the mixture which reaches the engine upon the closing of the throttle, such as tends to occur by the adding to the idling mixture leaving the carburetor of fuel which has collected on the manifold walls and the throttle ,disk .and shaft during an immediately preceding period of operation under low suction and low velocity.

In' the carburetor shown, fuel 10 in a float bowl 11 is supplied to a fuel nozzle 12, which discharges within a venturi 13; which receives primary air throughaprimary-air inlet opening 14. and projects' upward into and discharges within a mixing chamber 15. This mixing chamberl also receives secondary air from ak secondary-air supply passage16, with the detail of which this invention is not concerned. The outlet o-f the mixing chamber is controlled by a throttle 17, shown as of the usual butterfly or disk type mounted on a shaft 18 operated by an arm 19. The details of the carburetor so far described and ,used

may be varied as desired, and are not essential to my invention. v

Above the throttle 17 a hole 20 opens into the main passage. The effective size of this hole 20 may be controlled by a screw-plug. 21, which is screw-mounted in the outer end of such hole to close it, and has a stem extending 'along the holel for a considerable distance.

A number of such plugs are provided, with different diameters of stem, so that by the use of the proper pluor an desired effective size to'` the atmosphere. 1

of the hole may e o tained. The hole 20 communicates with a vertical passageway 22, the lower'end of which constitutes a valve seat., The passage 22When open, connects the hole'20 to a hole 23 or'23.` Desirablyl use the hole 23 (illustrated in Fig. l) which opens into the mixing chamber 15 to receive explosive mixture therefrom; yas that ar rangement has some advantage. Instead of the hole 23 from themixing chamber' 15, I may use the hole 23 (illustrated in Fig. 2) which opens-to the atmosphere, so that when the passage 21 is. open it connects the hole 2() A valvel 25 co-,operatesy with the valve seat at the lower end of the passage 22. This valve 25 is desirably a conical valve, formed at the upper end of a plunger 26. This plunger is movable'vertically in a tube 27, whichv has its upper portion mounted ina tube-receiving opening 28 in the main body of the carburetor and its lower portion dipping into the float bowl 11 and extending nearly to the bottom of such float bowl.

The plunger 26 desirably has its intermediate portion of smaller size than the interior of the tube 27, for reduction of friction; but has its upper end 29 and its lower end 30 of proper size to have a sliding fit in said tube.

The effective size of the hole 23 or 23 isidesirably adjustable. To this end, for example,

'the upper end 31 of the tube 27 may be cut off obhqnely, so that by turningthe tube on its axis it 1s possible to adjust the effective size of such hole 23, or 23. This adjustment, however, is ordinarily made once for all, and the tube 27 is then fastened in adjusted position by a lock-screw 32, which desirably cooperates with a circumferential groove 33 in the tube to hold the tubeat the proper height as well as in the proper angular position.

The lower end of the tube 27 is closed bya screw-plug 35, so that the lower part of such tube serves as a dash-pot cylinder in which the lower end 30 of the plunger v26 reciprocates as a dash-pot piston. At about the level vided with an upwardly opening check valve, n

so that the dash-pot formedby the lower ends of the plunger and tube will act to retard upward movement of theplunger but not to retardV downward movement thereof. This check valve is desirably a ball 40 normally resting in a seat at the upper end of a hollow ,y

screw-'plug 41 screwed into the bottom of the plunger 26 the ball when seated closing the opening 42 through such plug 41. The balll plays in a small chamber 43 provided in'the lowery end 30 ofl the plunger. The upper end lof such chamber 43 has a lateral outlet 44 to the-.surface of the plunger at the smaller intermediate portion thereof and in proximityto the opening 36 in the tube. y lIn operation, when' the suction above the throttle disk "17 is below a certain value, (or the pressure is .above a certain value), the plunger 26 drops in the tube27, because the weight of such plunger overcomes such suction. The dropping of the plunger is rapid, because the ball valve 40 opens as the plunger descends, to `permit fuel\to pass from beneath the plungerlout through the opening 42, the chamber 43,v and the openings 44 and 36.

Whenever the suction above the throttle disk rises sufficiently high, (or the pressure falls sufficiently low,) however, thus overcoming the weight of the, plunger 26, the plunger 26 rises. This rising is slow, because of the dash-pot action of the lower end 30 of the plunger in the lower end of the tube 27, for the ball 40 is on its seat in this up-y ward movement and free passage of the dashpot liquid is therefore prevented. vConsequently, it takes a definite time., of some length, for the plunger to make its full travel. When the plunger reaches the end of its upward -movement, it engages the valve seat at the lower end of thev passage 22, and thus shuts off the supply of explosive mixture or of air to the hole 20.

This eectively avoids stalling of the engine such as frequently occurs at the beginning of a period of idling after a period of operation at low suction and low air velocity.

During the operation. at low suction and low air velocity, a ,considerable vquantity of fuel has collected on the Walls of the mixture passage above the throttle, as well as on the throttle disk itself and its shaft. When vthe throttle is closed, and the vacuum above the throttle is increased, this collected fuel is losl added to thef mixture, to produce a mixture which is too rich to explode in the engine. this is prevented by my invention; because when the throttle 17 is first closed the mixture above the throttle is prevented from becoming too rich, by additional air which comes in as such or as the air of normal explosive mixture through the by-pass passage or conduit provided by the hole 20, the passageway 22, and the hole 23 or 23. The additional air thus admitted through the hole 20 into the space above the throttle keeps the mixture above the throttle suiiiciently lean to ensure capacity of explosion in the engine, andthe greater quantity of mixture reaching the engine keeps the engine speed slightly higher. This additional supply of air from the mixing chamber, or from the atmosphere, continues for only a short time, while the plunger 20 is rising, and is stopped when the valve 25 seats itself against the lower enelv of the passageway 22. This period of time, however, is suiiiciently long to dispose ofthe 4accumulated fuel; as the valve 25 does not seat itself until a` sufiicient period of time has elapsed for that. Thus during the beginning of an idling period, the idling is at higher than ordinary idling speed, by reason of the additional air which is admitted through the hole 20; but this higher idling speed continues for only a short time, during which this collected fuel is'used up, and then the valve 25 closes and the idling speed becomes normal. The time required for the Valve 25 to close may be varied by adjusting the tube 27 cireumferentially.

This also serves to facilitate starting, especially when the hole 22 is supplied by the hole 23 from the mixing chamber 15 asillusltrated in Fig. 1.V It is found by experience that an engine starts more easily if the throttle is partly open. When the engine is at rest, the plunger 26 is down, so thateven though the throttle 17 is closed explosive mixture may pass through the holes 23, 22, and 20 into the space above the throttle, to produce an effect equivalent to having the throttle partly open. This facilitates starting; but soon after the starting the suction developed above the throttle 17 draws up the plunger 26, and shuts off the additional supply of explosive mixture admitted through the hole 20, and cllets the engine operate at normal idling spee I claim as my invention 1. In combination, a carburetor mixing chamber into which air and fuel are suppliedv and from which a mixture-discharge passage leads, a throttle controlling said mixturedischarge passage, a conduit for admittingadditional air to said mixture-discharge passage on the engine side of the throttle when the throttle is closed, andfmeans for producing a delayed closing of said additional-air conduit following an increase above a predetermined value in the suction in said mixture-discharge passage on the engine side of said throttle.

2. In combination, a carburetor mixing chamber into which air and fuel are supplied and from which a mixture-discharge passage leads, a throttle controlling said mixturedischarge passage, a conduit for admitting additional mixture from said mixing chamber to said mixture-discharge passage on the engine side of the throttle when the throttle is closed, and means for producing a delayed closing of said additional-mixture conduit following an increase above a predetermined value in the suction in said mixture-discharge passage on the engine side of said throttle.

3. In combina-tion, a carburetor mixing chamber into which air and fuel are supplied and from which a mixture-discharge passage leads, a throttle controlling said mixturedischarge passage, .operating means for said throttle, and means for delaying the complete resultant decrease inthe air supply to said mixture-discharge passage 011 the engine side of said throttle when said throttle-operating means is moved to cut down the quantity of the mixture discharge through said mixturedischarge passage.

4. In combination, a carburetor mixing chamber into which air and fuel are supplied and from which a mixture-discharge passage leads, a throttle controlling said mixturedischarge passage, operating means for said throttle, and means for delaying the complete resultant decrease in the mixture supply from said mixing chamber to said mixture-discharge passage on the engine side of said throttle when said throttle-operating means is moved to cut down the quantity of the mixture discharge through Vsaid mixturedischarge passage.

5. In combination, a carburetor mixing chamber into which air and fuel are 'supplied and from which a mixture-discharge passage leads, a throttle controlling said mixturedischarge passage, a conduit for admitting chamber into which air and fuel are supplied and from which a lmixture-discharge passage leads, a throttle controlling said mixturedischarge passage, a conduit for admitting i additional air into said mixture-discharge passage on the engine side 0f said throttlel and a valve for closing said .additional-air conduit, said valve being operable by engine suction and having a tendency to move to open position but being associated with said '5 mixture-discharge passage so that it tends to move to close said additional-air conduit 'uponan increase to a predetermined value in the suction in said mixture-discharge passage on the engine side of the throttle.

l. In combination, a carburetor mixing chamber into which air and fuel are supplied and from which a mixture-discharge passage leads, a throttle controlling said mixturedischarge passage, a fuel chamber containing 15 fuel to be supplied to said vmixing chamber,

a conduit for admitting additional air into said mixture-discharge passage on the engine side of the throttle, a va'lvepfor controlling said additional-air conduit, a plunger assom ciated with said valve to operate it, said plunger having a'tendency to move to a position to open said valvey but being subject to the suctionin said mixture-discharge passage so that such suction tends to move it tov g5 close said valve, and a dash-pot for retarding the movement of said plunger in the direction to close said valve, -said dash-pot being a liquid dash-pot arranged to receive its liuid from said fuel chamber.

30 8. n combination, a carburetor4 mixing chamber into which air and fuel are supplied and from which a mixture-discharge passage leads, a throttle controlling said mixture-- discharge passage, a conduit for admitting- 35 additional air into said mixture-discharge passage on the engine side of the throttle, a valve for controlling said additional-air conduit, a plunger associated with said valve to operate it, said plunger having a tendency o to move to a position to open said valve but being subject to the suction in said mixturedischarge passage so that such suction tends to move it to close said valve, and a dash-pot for retarding the movement of said plunger 5 in the direction to close said valve.

In Witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this' 11th day of March, A. D. one thousand nine hundred and twenty-five.

HOWARD W. LINKERT. 

